Device for continuous mixing of materials

ABSTRACT

A method and a device for the continuous mixing of at least two materials of which one can be pumped and providing a tank for the mixing process in which the material to be mixed is caused to circulate by means of a feed pump.

United States Patent Lage [54] DEVICE FOR CONTINUOUS MIXING OF MATERIALS [72] Inventor: Jaime Richard Lage, Umiken, Switzerland [73] Assignee: F. Barry Haskett, Versoix, Geneva, Switzerland [22] Filed: Jam3l, 1969 [21] Appl.No.: 795,529

[30] Foreign Application Priority Data Feb. 2, 1968 France ..l39497 [52] US. Cl ..259/95, 259/4 [51] Int. Cl. ..B0lf 5/12 [58] Field of Search ..259/4, 95, 96, 97, 98, I8,

[ 51 May 9, 1972 [56] References Cited UNITED STATES PATENTS 1,706,418 3/ I 929 Sissom ..259/95 l,7l4,888 5/1929 Perkins..... 3,334,868 8/1967 Lage ..259/95 Primary Examiner-Robert W. Jenkins Attorney-Sherman & Shalloway s7 ABSTRACT A method and a device for the continuous mixing of at least two materials of which-one can be pumped-and providing a tank for the mixing process in which the materialto be mixed is caused to circulate by means of a feed pump.

2 Claims, 1 Drawing Figure This invention relates to a device for the continuous mixing of at least two materials of which at least one canbe pumped, a tank being used for the mixing process in-which the material to be mixed is caused to circulate by means of a feed pump.

In one known mixing device part of the materials to be mixed are withdrawn from the surface at one comer or section of the tank and reintroduced centrallyin the vicinity of the tank bottom. The circulation of the mixture due to part ofthe material being returned to the tank in the form of three streams, is not controlled, 'the mixing effect is not uniform, and there is no certainty that the entire material particupates in' the circulatory movement.

In another mixing device also part of the tank contents are withdrawn laterally and are reintroduced centrally in the vicinity of the tank bottom, but withthis device measures are taken to insure that the stream of material which is discharged has a uniform and predetermined circulatory movement with very long flow paths. Only a small part of the fresh'material which has to be mixedand reaches the tank travels only once along the flow path because a part of the mixture is constantly being discharged and passed again back into the tank. By far the greater part of the-materialtraVels several times around the flow path. In this way a much moreintensive mixing is achieved, but this of course-requires a correspondingly larger power input for the necessary pumping capacity.

Mixing processes are known, such as introducing-gases into liquids, where a very high degree of miscibility is required but only a short flow path in the mixing tank is adequate. The object of the present invention is to produce an expedient device for such processes whereby the pumping power required per unit throughout can be considerably reduced when compared with that required with conventional devices. According to the invention this problem is solved in that at least a part of the fresh material which flows to the mixing device is continuously passed into the mixing tank by way of a central supply pipe, the outlet of which is constructed in the form of a pressure nozzle that is located only slightly above. the'bottom. of the mixing tank which uniformally diverts the flow which is discharged from the nozzle radially in all directions.

A constructional example of the invention is shown diagrammatically in the accompanying drawing which is a vertical cross-section of the apparatus.

The fresh materials that are to be mixed flow under pressure in the direction indicated by the arrow 1 through a supply pipe 11 towards the mixing device and by means of a supplydevice 2, hereafter briefly referred to as a pump, are conveyed through a feed pipe 5 into the mixing tank 4. The outlet of.

supply pipe 5 is constructed in the form of a pressure nozzle 6 with a restricted discharge section and is located slightly above the bottom of the mixing tank4. The jet from the noule impinges against the bottom of the tank where-it is diverted radially in all directions in a uniform manner. The material in the tank is thus subjected to a rotationally symmetrical circulatory movement with a return flow to the starting point along closed flow paths which are indicated by the arrows 8. The mixed material emerges from the tank by way of a discharge pipe 7. Due to the influence of the'lateral discharge the circulatory movement is transformed into a spiral movement, the axis of the spiral being arcuate. The individual particles of the fresh material which is supplied to the tank by way of the pipe 5, travel not morethan once along theentire spiral flow path, that is in the drawing from the right side of the tank to the discharge pipe 7 on the left hand side, this depending upon the direction in which the particles are diverted after they emerge from the nozzle. As a result of the impact of the jet of material on the tank bottom as it is discharged from the pressure noule and the rotating circulatory movement of the mixture, a very intense mixing effect is achieved, when the conveying power is suitably selected.

The throughput or travel of the material can be controlled in a suitable manner. For example, a device can be provided to vary the amount of material passing through the supply pipe 11 to the mixing tank or by varying the speed of the feed pump 2.

In the .case of materials-which can easily'be mixed, it is not necessary that theentire quantity of fresh material should pass through the supplypipe'Sinto the mixing tank and due to the impact onthe tank bottom undergo a primary mixing and also the circulating movement in the mixing tank can be less turbulent sothat it is thenan advantage to provide a connecting pipe 3 between the supply pipe 11 andthe mixing tank 4.

a When the amount of material passing to the mixing device exceeds the capacity of the pump, part of the material then bypassesthe pump-and flows through'the connecting pipe 3 directly into the mixing tank 4. Due to the circulating movement in the tank the part of the material which passes through .a bypass is alsocarried along and mixes with the material in the tank. It isthus possible to reduce the'power required by the pumpperthroughputunit, to a-value which is in keeping with the surplus amount of material supplied to the pump when compared with the pumping capacity of the latter.

By means of the connection pipe 3 it is possible to influence the mixing intensity of the device in a very simple manner. If the output of the pump is kept constant, it is only necessary to vary theamount of fresh material that is supplied to the mixing device. If this amount exceeds the output of the pump very considerably, then a large part of the material will pass through the connection pipe 3 into the tank and the throughput or capacity of the device is increased but the mixing intensity is diminished. As the supply of material decreases, the part of the material which is directly bypassed into the tank decreasesand is finally zero when the amount of material supplied to the tank exactly corresponds to the output capacity of the pump. The mixing intensity has then increased and no more material flows through the connection pipe even when the throttle valve 10, located in pipe 3, is

material back into the tank. The smaller the amount of fresh material, the better will be the mixing'effect achieved in the tankand the smaller the throughput or flow, the greater will be the pumping power per throughput unit.

The possibility of allowing'the material to pass through the connection pipe 3 in either direction is indicated in the drawing by the double arrow 9. The throttle valve '10 enables an additional individual adjustment to be obtained in order to accommodate various operatingrequirements so that very flexible hydraulic conditions can be achieved.

The described device serves primarily for materials that can easily be mixed, and itis characterized by its high efficiency, because depending on'the materials it is desired to mix and the required mixing intensity an optimum adjustment can be obtained whereby only a minimum amount of power per unit throughput is required.

I claim:

-l.- Devicefor continuously mixing at least two materials, at least one of which can bepumped, comprising a feed pump, a

supply pipeto said feed pump-through which fresh material to fecting a uniform deviation of a jet of material issuing from said nozzle, a device for varying the quantity of material flowing into said mixing device, a connection pipe between said supply pipe to said feed pump and said mixing tank, and a throttle valve in said connection pipe, whereby fresh material can be introduced into said mixing tank through said throttle capacity of said pump, a part of the fresh material bypasses the pump by means of a connection pipe and passes directly into said mixing tank, and when the capacity of the pump exceeds the amount of fresh material, the deficit in material is taken from said mixing tank through the connection pipe and passed together with the fresh material back into said mixing tank. I 

1. Device for continuously mixing at least two materials, at least one of which can be pumped, comprising a feed pump, a supply pipe to said feed pump through which fresh material to be mixed flows, a mixing tank in which a circulatory movement of material is produced by said feed pump, a central feed pipe connecting said feed pump with said mixing tank, at least part of the fresh material supplied to the mixing tank being conveyed by said pump into said mixing tank by way of said central feed pipe, the open end of said central feed pipe being constructed in the form of a pressure nozzle with a restricted outlet, said pressure nozzle being located slightly above the bottom of said mixing tank, said bottom of said mixing tank effecting a uniform deviation of a jet of material issuing from said nozzle, a device for varying the quantity of material flowing into said mixing device, a connection pipe between said supply pipe to said feed pump and said mixing tank, and a throttle valve in said connection pipe, whereby fresh material can be introduced into said mixing tank through said throttle valve and connection pipe, and material can be withdrawn from said mixing tank through said connection pipe and throttle valve.
 2. Method of operating a mixing device comprising maintaining the output of a pump pumping material into said mixing device at least approximately constant and varying the amount of fresh material supplied to said mixing device, whereby when said amount of fresh material exceeds the capacity of said pump, a part of the fresh material bypasses the pump by means of a connection pipe and passes directly into said mixing tank, and when the capacity of the pump exceeds the amount of fresh material, the deficit in material is taken from said mixing tank through the connection pipe and passed together with the fresh material back into said mixing tank. 